Methods, test systems and arrangements for verifying compliance with requirement specifications

ABSTRACT

A method for verifying compliance of a communication device with one or more requirement specifications is disclosed. The method comprises establishing a link between a test system and the communication device, wherein the establishing comprises configuring one or more bearers and one or more control channels; closing a test loop comprising the test system and the communication device, wherein the closing comprises activating a test loop function of the communication device; sending data in a downlink of the test loop from the test system to the communication device; receiving the data at the communication device; transferring at least some of the data to an uplink transmission arrangement of the communication device after a specific event has occurred; and verifying, at the test system, transmission in an uplink of the test loop from the communication device to the test system. Corresponding test system and test loop function arrangement are also disclosed.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/990,718, which was filed on Jan. 5, 2011, which is anational stage application of PCT/EP2009/055455, filed May 6, 2009, andclaims benefit of U.S. Provisional Application 61/051,117, filed May 7,2008, U.S. Provisional Application 61/061,179 filed Jun. 13, 2008, andEP09151171.7 filed on Jan. 23, 2009, the disclosures of each of whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates generally to the field of verifyingcompliance with requirement specifications. More particularly, itrelates to verifying compliance of a communication device withrequirement specifications regarding uplink transmission and/or downlinkreception.

BACKGROUND

In the course of developing standardizations for communicationtechnologies, requirement specifications are often provided. Therequirement specifications are developed to support requirement testingof communication devices and to be used in such conformance testactivities. The purpose of the requirement testing is to show that acommunication device is compliant with the relevant communicationstandard this is shown by demonstrating fulfillment of the requirementspecifications. Various requirement (or test) specifications commonlycover different aspects of the relevant standard such as, for example,compliance with control signaling aspects, correct data transfer, andperformance within certain limits under certain conditions.

A common way to perform requirement testing of communication devices isto connect the communication device to a test tool (test system) and letthe test system initiate different aspects of the communication devicefunctionality. The test system then verifies that the communicationdevice performs its tasks in compliance with the requirementspecifications.

When terminal communication devices are to undergo requirement testing,a common prerequisite to enable test automation and to achieverepeatability of test results is that the terminal communication devicecomprises some specific test functions.

When testing certain aspects of communication standards, MobileOriginated (MO) data transfer is required. Mobile Originated data refersto data that is to be transmitted from a terminal communication deviceto a communication network, for example data transmitted in an uplink(UL) of a radio link in UTRA (UMTS Terrestrial Radio Access). To enabletesting of such scenarios, test functions in the terminal communicationdevice are needed to trigger and generate MO data transfer in the uplink(i.e. data transmission by the device under test).

To this end, the specific test functions in the terminal communicationdevice may comprise a function adapted to loopback data. For example,such a function may be adapted to return data that was transmitted bythe test system to the terminal communication device by transmitting thesame data back to the test system.

This technique to loopback data is commonly used to test compliance inrelation to different communication technologies, for example mobilecommunications technologies in relation to UTRA as specified in the 3GPP(3^(rd) Generation Partnership Project) specification TS 34.109“Terminal logical test interface; Special conformance testingfunctions”.

Examples of communication standards relevant for the purposes ofembodiments of the present invention are GPRS (General Packet RadioService), UMTS (Universal Mobile Telecommunication Standard) and UMTSLTE (UMTS—Long Term Evolution). In the following the description ofproblems, which arise in connection with existing requirement testingmethods and devices, and of the solutions thereof according toembodiments of the invention will be described with focus on UMTS LTE.It is emphasized, however, that the invention is by no ways limited tothis communication standard, bur is equally applicable to requirementtesting in relation to other communication as will be readily understoodby the skilled person.

It is to be noted that all references to 3GPP specifications are to beunderstood as references to the versions of the specifications aspublished on the home page of 3GPP on May 6, 2008.

The 3GPP standard for UMTS LTE specifies how a terminal communicationdevice should behave when it has data pending for transmission in theuplink. In order to verify such behavior, specific test functions totrigger and generate data for transmission in the uplink are required.In TS 34.109 referenced above, test functions have been defined for UTRAthat perform loopback of data received from the test system in thedownlink (DL) so that the data is returned in the uplink. In the testfunctions defined in TS 34.109 each data unit received in the downlinkis directly returned in the uplink. Further, these test functions arebased on that data units received in the downlink on a bi-directionalradio bearer is directly forwarded to the uplink for transmission on thesame radio bearer.

In order to be able to verify the terminal behavior for certainscenarios, there is a need to have means to control (e.g. from the testsystem) when the data sent in the downlink is to become available fortransmission in the uplink in the terminal. Such a scenario might be aconnection re-establishment after radio link failure when the terminalhas data pending for transmission in the uplink (see e.g. R5-081618(available fromftp://www.3gpp.org/tsg_ran/WG5_Test_ex-T1/TSGR5_(—)39_KansasCity/Tdoc/R5-081618.zip),3GPP RAN5 work plan for TS 36.523-1; R5-081618 is to be included in TS36.523-1, “Evolved Universal Terrestrial Radio Access (E-UTRA) andEvolved Packet Core (EPC); User Equipment (UE) conformancespecification; Part 1: Protocol conformance specification”).

Similarly, there is also a need to be able to verify terminalcommunication device behavior for certain mobility scenarios, forexample for a handover between different radio access technologies(RATs) (see e.g. R5-081618 as specified above).

To be able to verify terminal behavior for such scenarios, the testsystem needs to be able to control the timing relation between certainevents and actions in the test procedure.

The 3GPP specifications TS 23.401, “General Packet Radio Service (GPRS)enhancements for Evolved Universal Terrestrial Radio Access Network(E-UTRAN) access” and TS 24.301, “Non-Access-Stratum (NAS) protocol forEvolved Packet System (EPS); Stage 3” define terminal behavior inrespect of how the terminal should map Service Data Flows (SDF) toEPS-bearers to achieve necessary QoS (Quality of Service) based on aconfigured filtering mechanism (UL TFT—Uplink Traffic Flow Template). ULTFT is an example of packet filtering which is a more general termapplicable also to other communication standards. The UL TFT may, forexample, specify type(s) of service, port number(s), etc for differentService Data Flows. Similar functionality for how the uplink IP(Internet Protocol) packet flows are mapped to the correct bearer (e.g.the correct PDP (Packet Data Protocol) context) via UL TFT is alsodescribed in TS 23.060, “General Packet Radio Service (GPRS); Servicedescription; Stage 2” and TS 24.008, “Mobile radio interface Layer 3specification; Core network protocols; Stage 3”.

Test loops, such as those specified in TS 34.109 as reference above, donot provide loopback functionality required to verify correct UL TFThandling by the terminal device. Thus, means are needed to be able totest correct behavior of the terminal in respect of UL TFTfunctionality. There is a need to test handling of UL TFT within a sameradio access technology. If for example new EPS-bearers or PDP-contextsare activated, or EPS-bearers or PDP-contexts are released or modifiedwhile the terminal remains within one and the same RAT. There is also aneed to test handling of UL TFT when the terminal experiences a handoverbetween radio access technologies. For example, after an E-UTRA to UTRAhandover, EPS-bearers are replaced by PDP-contexts. Thus, correcthandling of this situation in relation to UL TFT needs to be verified.

Therefore, there is a need for methods, arrangements and test systemsthat enables requirement testing of scenarios where the timing relationbetween certain events and actions in the test procedure needs to becontrolled. There is also a need for methods, arrangements and testsystems that enables requirement testing of scenarios where packetfiltering is applied.

SUMMARY

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps, or components, but does not preclude thepresence or addition of one or more other features, integers, steps,components, or groups thereof.

It is an object of the invention to obviate at least some of the abovedisadvantages and to provide improved methods, test systems andarrangements for verifying compliance with requirement specifications.

According to a first aspect of the invention this is achieved by amethod for verifying compliance of a communication device with one ormore requirement specifications. The method comprises establishing alink between a test system and the communication device, wherein theestablishing comprises configuring one or more bearers and one or morecontrol channels; closing a test loop comprising the test system and thecommunication device, wherein the closing comprises activating a testloop function of the communication device; sending data in a downlink ofthe test loop from the test system to the communication device;receiving the data at the communication device; transferring at leastsome of the data to an uplink transmission arrangement of thecommunication device after a specific event has occurred; and verifying,at the test system, transmission in an uplink (116) of the test loopfrom the communication device to the test system.

In some embodiments, the step of verifying transmission in the uplinkmay comprise verifying that the data transferred to the uplinktransmission arrangement is transmitted correctly in the uplink by thecommunication device.

In some embodiments, the specific event may be one or more of the elapseof a specific amount of time from the reception of the data, atransmission of a specific command from the test system to thecommunication device, and a registration of a test operator actionperformed on at least one of the test system and the communicationdevice.

In some embodiments, the specific event may be a disconnection of thelink. In such embodiments, the method may further comprise verifying, atthe test system, that a link re-establishment procedure is executedcorrectly by the communication device.

In some embodiments, the method may further comprise disconnecting thelink after the step of sending the data in the downlink and before thespecific event has occurred; and verifying, at the test system, that alink re-establishment procedure is executed correctly by thecommunication device.

The link may be a radio link and the bearers may be radio bearers insome embodiments.

The method may, in some embodiments, further comprise simulating anintra-system cell handover event by transmitting a cell handover commandfrom the test system to the communication device after the step ofsending the data in the downlink and before the specific event hasoccurred; and verifying, at the test system, that an intra-system cellhandover procedure is executed correctly by the communication device.

The method may, in some embodiments, further comprise simulating a radioaccess technology handover event by transmitting a radio accesstechnology handover command from the test system to the communicationdevice after the step of sending the data in the downlink and before thespecific event has occurred; and verifying, at the test system, that aradio access technology handover procedure is executed correctly by thecommunication device.

In some embodiments, the step of activating the test loop function maycomprise sending an indicator defining the specific event from the testsystem to the communication device.

In some embodiments, the step of establishing the link between the testsystem and the communication device may further comprise configuring oneor more uplink packet filters; the step of sending data in the downlinkof the test loop from the test system to the communication device maycomprise sending units of data associated with different service dataflows and including, in each of the units of data, informationrepresenting the service data flow associated with the unit of data; andthe step of verifying transmission in the uplink may comprise verifyingthat each of the units of data is transmitted, by the communicationdevice, on a correct bearer corresponding to the service data flowassociated with the respective unit of data according to the one or moreuplink packet filters.

A second aspect of the invention is a computer program productcomprising a computer readable medium, having thereon a computer programcomprising program instructions, the computer program being loadableinto a data-processing unit of a test system connectable to acommunication device for verifying compliance of the communicationdevice with one or more requirement specifications and adapted to causethe test system to execute, when the computer program is run by thedata-processing unit, at least the steps of: establishing a link betweenthe test system and a communication device, wherein the establishingcomprises configuring one or more bearers and one or more controlchannels; closing a test loop comprising the test system and thecommunication device, wherein the closing comprises activating a testloop function of the communication device; sending data in a downlink ofthe test loop from the test system to the communication device; andverifying transmission in an uplink of the test loop from thecommunication device to the test system. The step of activating the testloop function comprises sending an indicator defining a specific eventfrom the test system to the communication device, wherein the specificevent is for controlling when the communication device transfers atleast some of the data to an uplink transmission arrangement of thecommunication device.

A third aspect of the invention is a computer program product comprisinga computer readable medium, having thereon a computer program comprisingprogram instructions, the computer program being loadable into adata-processing unit of a communication device and adapted to cause atest loop function of the communication device to execute, when thecomputer program is run by the data-processing unit, at least the stepsof: receiving an indicator defining a specific event from a test systemas part of an activation of a test loop function of the communicationdevice; receiving data in a downlink of the test loop from the testsystem; and transferring at least some of the data to an uplinktransmission arrangement of the communication device after the specificevent has occurred.

A fourth aspect of the invention is a test system connectable to acommunication device and for verifying compliance of the communicationdevice with one or more requirement specifications. The test systemcomprises a transmitter, a receiver and processing circuitry. Theprocessing circuitry is adapted to: establish, via the transmitter, alink between the test system and the communication device, wherein theestablishing comprises configuring one or more bearers and one or morecontrol channels; and close, via the transmitter and the receiver, atest loop comprising the test system and the communication device,wherein the closing comprises activating a test loop function of thecommunication device. The transmitter is adapted to send data in adownlink of the test loop from the test system to the communicationdevice, and the receiver and the processing circuitry are adapted toverify transmission in an uplink of the test loop from the communicationdevice to the test system. The processing circuitry is also adapted tosend, via the transmitter, an indicator defining a specific event fromthe test system to the communication device as part of the activation ofthe test loop function, wherein the specific event is for controllingwhen the communication device transfers at least some of the data to anuplink transmission arrangement of the communication device.

A fifth aspect of the invention is a test loop function arrangement forintegration into a communication device. The arrangement comprises atest control function unit; and a loop back function unit adapted toreceive data sent in a downlink of the test loop from a test system andto transfer at least some of the data to an uplink transmissionarrangement of the communication device. The test control function unitis adapted to: receive an indicator defining a specific event from thetest system as part of activation of the test loop function arrangement;and defer transferring by the loop back function unit of the data to theuplink transmission arrangement until after the specific event hasoccurred.

A sixth aspect of the invention is a communication device comprising thetest loop function arrangement according to the fifth aspect.

A seventh aspect of the invention is an arrangement for verifyingrequirement specifications comprising at least the test system accordingto the fourth aspect and the communication device according to the sixthaspect.

In some embodiments, the second through seventh aspects of the inventionmay additionally have features identical with or corresponding to any ofthe various features as explained above for the first aspect of theinvention.

A test loop as referred to in this application comprises a test loopfunctionality of a communication device. The communication device is thetest object. The test loop further comprises a test system adapted toautomate testing of the communication device.

An advantage of some embodiments of the invention is that requirementtesting is enabled of scenarios where the timing relation betweencertain events and actions in the test procedure needs to be controlled.

Another advantage of some embodiments of the invention is that it ismade possible to verify terminal communication device compliance inrelation to scenarios with MO data transfer

Another advantage of some embodiments of the invention is that scenarioswhere a connection re-establishment should be made due to that data ispending for transmission in the terminal may be tested.

Another advantage of some embodiments of the invention is thatrequirement testing is enabled of scenarios where packet filtering isapplied.

Another advantage of some embodiments of the invention is that scenarioswhere an inter-system handover takes place may be tested.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of the invention will appearfrom the following detailed description of embodiments of the invention,with reference being made to the accompanying drawings, in which:

FIG. 1 is a signaling flowchart illustrating example method stepsaccording to some embodiments of the invention;

FIG. 2 is a block diagram illustrating an example test system and anexample arrangement comprised in a communication device according tosome embodiments of the invention;

FIG. 3 is a block diagram illustrating an example test system and anexample arrangement comprised in a communication device according tosome embodiments of the invention;

FIG. 4 is a signaling flowchart illustrating example method stepsaccording to some embodiments of the invention; and

FIG. 5 is a block diagram illustrating example IPv4 header fields.

DETAILED DESCRIPTION

In the following, embodiments of the invention will be described wheremethods and apparatuses are described which are suitable for use intesting of compliance with one or more requirement specifications.

The test functions defined in TS 34.109 as referenced above do notenable any control of the triggering or timing of the data transfer inthe uplink. Contrarily, each data unit received in the downlink isdirectly returned by the test function of the terminal communicationdevice for transmission in the uplink. Furthermore, data units receivedin the downlink on a bi-directional radio bearer is directly forwardedfor transmission in the uplink on the same radio bearer. The timingaspects for the loopback of data as specified in TS 34.109 arerestricted to that the terminal, within certain conditions, shall keepthe loopback delay constant. The loopback delay cannot be controlled bythe test system, but is simply specified as a maximum delay value.

In order to be able to verify the terminal behavior for certainscenarios, there is a need to have means to control (e.g. from the testsystem) when the data sent in the downlink is to become available fortransmission in the uplink in the terminal. Such a scenario might be aconnection re-establishment after radio link disconnection (e.g. due toradio link failure) since the terminal has data pending for transmissionin the uplink. Another example scenario may be that data is pendingafter a handover to another radio access technology or to another cellwithin the same radio access technology.

To be able to verify correct behavior in such scenarios it is crucial tobe able to control the timing relation between the disconnection of thelink (or the handover) and the triggering of data transmission in theuplink.

In the case of radio access technology (RAT) handover it is alsoimportant to be able to verify continuation of data transmission beforeand after the RAT handover. Thus, a test loop must be provided that canbe maintained throughout the RAT handover, i.e. the test loop should notbe canceled due to radio access system changes. For this purpose a radioaccess transparent test loop mode is needed.

FIG. 1 is a signaling flowchart illustrating example method stepsaccording to some embodiments of the invention and the interactionbetween a test system 100 and a communication device 110 under test.

The test system 100 is configured to send data to the communicationdevice 110 in a downlink and the communication device 110 is configuredto return data received in the downlink for transmission in the uplinkto the test system 100. The communication device 110 is furtherconfigured to return data for transmission in the uplink only after aspecific event has occurred. This enables control over the relativetiming of certain events and actions in the test procedure. For example,the test system may trigger a disconnection of the link before thespecific event has occurred and thereby ensure that the communicationdevice will have data pending for transmission when the link has beendisconnected. Thereby the test system is able to ensure the possibilityto verify the connection re-establishment procedure and that data iscorrectly transmitted after the connection re-establishment.

In step 101, the test system establishes a radio link, and configuresthe radio bearer(s) and control channel(s) to be used for the test.

In step 102, the test system triggers activation of the dedicated testloop function of the communication device, which responds to theactivation triggering in step 111. The activation in steps 102 and 111may comprise closing of a test loop. The activation may also compriseconfiguring the test loop function. Alternatively, the test loopfunction may be partly or fully pre-configured.

In step 103, the test system sends data (e.g. IP packets or layer 2 dataunits) in the downlink to the communication device, which receives thedata in step 112. In step 112, the data received by the communicationdevice may also undergo various processing by the communication device,for example such internal device reception data processing as known inthe art. After step 112 (e.g. in connection with steps 116 and 107),verification that the reception of data and the processing of thereceived data are performed correctly by the communication device may beundertaken.

The dedicated test loop function is configured to transfer all or partof the data received in downlink for transmission on a radio bearer inthe uplink (step 114). However, the dedicated test loop function isfurther configured to only transfer the data for transmission in theuplink after a specific event has occurred (step 113).

The specific event may be the elapse of a specific amount of time fromthe time the data has been received. This may be realized as a timer inthe test loop function. The time may be pre-configured or it may beconfigured (e.g. by the test system) as part of the activation in steps102 and 111. It may also be configured by a specific command entered oneither or both of the test system and the communication device prior toor after the test function has been activated in steps 102 and 111.

The specific event may also be another event such as the transmission ofa specific command from the test system to the communication device(step 105), the registration of an action (such as pressing a key)performed by a test operator on either or both of the test system (step105) and the communication device. The specific event may also be thedisconnection (104) of the radio link established in step 101.

The type of event (elapsed time, command, operator action, linkdisconnection, etc.) may be pre-configured or it may be configured (e.g.by the test system) as part of the activation in steps 102 and 111. Thetest system may send an indicator to the communication system thatdefines the type of event and/or the amount of time to elapse. It mayalso be configured by specific commands entered on either or both of thetest system and the communication device prior to or after the testfunction has been activated in steps 102 and 111.

The solution with a specific elapsed time has little impact on theimplementation of the communication device.

After the communication device has transferred the data for transmissionin the uplink in step 114, the same data is transmitted in the uplink instep 116, and receiver by the test system in step 107. When the testsystem receives the data in step 107, it can do verification of thedata. The verification may simply comprise verifying that uplinktransmission takes place without verifying that the data is actuallycorrect, or it may comprise also verifying that the data is transmittedcorrectly in the uplink.

As mentioned above, the verification may additionally or alternativelycomprise indirect verification of correct DL reception and/orprocessing. Such verification is indirect because the verification isperformed via returned (UL) data. The test system compares the returnedUL data with the data that was sent in the DL. If, for example, thereturned UL data is identical with the data that was sent in the DL,this may be verification that the reception and processing of the DLdata was performed correctly. Another example is where a test systemsends DL data with erroneous header information. Then, the communicationdevice should not accept the data and correct operation of thecommunication device may be verified in that no data is returned in theUL.

When the test session is completed, the test system triggers thedeactivation (opening) of the test loop in step 108, and thecommunication device responds to the deactivation triggering in step117. In step 109, the radio link is disconnected.

Before the specific event has occurred, the test system may trigger adisconnection of the radio link between the test system and thecommunication device under test in step 104.

When the test loop function in the communication device has returneddata received in downlink for transmission in the uplink (step 114), theradio link may thus be disconnected. Since the communication device isdisconnected and has data pending for transmission in the uplink, aprocedure to re-establish the connection is triggered in step 115.

The test system verifies, in step 106, that the communication deviceperforms the connection re-establishment procedure correctly.

The disconnection in step 104 may, for example, simulate a radio linkfailure. Alternatively or additionally, the test system may, before thespecific event has occurred, simulate handover to other intra-systemcell or to other RAT and verify that the communication device performsthe corresponding procedures correctly. In this case, the specific eventmay comprise any of the examples as referred to above or it may comprisethe handover in itself.

As mentioned, the test loop function in the communication device may beconfigured to return part or all of the data received on the downlink.For example, some of the data sent in the downlink may be intended forthe uplink (e.g. for testing uplink behavior) and is thus returned,while some of the data sent in the downlink may be intended for someother purpose (e.g. for testing of downlink reception) and is thus notreturned. Furthermore, if the data is transmitted as packets (e.g. IPpackets) in the downlink, it may be only the payload of the packet thatis returned for transmission in the uplink. Other content of the packet(such as header information), may be removed, added or changed beforetransmission in the uplink. The size of the payload may also be changed,for example by repeating the entire or part of the payload, bytruncating or puncturing the payload. Furthermore, the size of theentire packet may be changed, if for example the header is changedand/or the size of the payload is changed.

As mentioned the test loop function may be partly or fullypreconfigured. There may be a dedicated preconfigured test loop functionfor each relevant scenario. Alternatively, there may be a single (or afew) test loop functions, which are configured for a specific scenarioas part of the activation in steps 102 and 111.

Links and bearers have been described above as radio links and radiobearers, but embodiments of the invention are equally applicable towired communication systems.

Some embodiments of the invention combine elapsed time and another eventtriggering in the same solution. For example, the data may betransferred in step 114 directly after an event trigger (105) but at thelatest at the elapse of a specific amount of time.

In TS 34.109 (FIG. 5.1.1), a UE test loop function is defined thatprovides loopback of data for bidirectional radio bearers.

FIG. 2 is a block diagram illustrating an example test system 200 and anexample test loop function arrangement 310 comprised in a communicationdevice 300 according to some embodiments of the invention.

The test system 200 and the communication device 300 may, for example,correspond to the test system 100 and the communication device 110 andthe test system 200 and the arrangement 310 may be adapted to performmethod steps as described in relation to FIG. 1.

The test system comprises a transmitter 201, a receiver 202 andprocessing circuitry (e.g. a central processing unit—CPU) 203. Theseentities may be adapted to perform method steps as described inconnection to the test system 100 of FIG. 1.

The test loop function arrangement 310 comprises a test control unit(TC) 311 and a loop back (LB) function unit 312.

According to embodiments of the invention, the LB function unit 312 mayinclude one or more radio bearer loop back (RB LB) entities (not shown).In TS 34.109 (FIG. 5.1.1) a loop back function unit with several radiobearer loop back (RB LB) entities (one per DL/UL RB pair) is shown. EachRBLB entity may be configured to return all or part of the data receivedfrom one downlink radio bearer (or a control channel) to an uplink radiobearer. Alternatively, a RBLB entity may be configured to return all orpart of the data received from any downlink radio bearer (or a controlchannel) to any of the configured uplink radio bearers, possibly basedon some mapping rules.

The TC function unit 311 is used to control the LB function unit 312.The TC function unit may receive commands via a user interface of thecommunication device 300, via messages received on an interface externalto the communication device 300, or via a radio interface (e.g. E-UTRAradio interface) under testing. An advantage with the latter is that nospecial external interface needs to be mandated in all devices that areto be tested. For example, a built-in PC module compliant with theUTRA/E-UTRA specification is not required to have an extra externalinterface (e.g. USB) just for conformance test purposes if this approachis used. The TC function unit provides control over activation andde-activation of the test loop function, over establishment andconfiguration of RB LB entities, over closing and opening of the testloop, and over event/time delay configuration. The LB function unit isadapted to receive downlink data and to transfer some or all of thatdata for transmission in the uplink. The transferring of the data may bedone under the control of the TC function unit.

The loopback point resides above the access functionality of thecommunication device, i.e. in a non-access stratum.

The test system 200 and the communication device 300 may furthercomprise input/output interfaces as generally known in the art. Theseinterfaces may, for example, comprise keys and display(s) and may beused by a test operator when conducting, controlling and monitoring thetest.

FIG. 3 is a block diagram illustrating an example test system 220 and anexample test loop function arrangement 330 comprised in a communicationdevice 320 according to some embodiments of the invention.

The test system 220 and the communication device 320 may, for example,correspond to the test system 400 and the communication device 410 ofFIG. 4, and the test system 220 and the arrangement 330 may be adaptedto perform method steps as will be described in relation to FIG. 4.

The test system comprises a transmitter 221, a receiver 222 andprocessing circuitry (e.g. a central processing unit—CPU) 223. Theseentities may be adapted to perform method steps as will be described inconnection to the test system 400 of FIG. 4.

The test loop function arrangement 330, which may be comprised in thecommunication device 320, comprises a test control unit (TC) 331 and aloop back (LB) function unit 332 similar to the corresponding units 311and 312 of FIG. 2. The communication device 320 further comprises abearer mapping unit 333. The bearer mapping unit 333 may be configuredto map data to be transmitted in the uplink to their respective bearerin accordance with corresponding packet filters. The packet filtersspecify on which bearer data associated with a particular service dataflow should be mapped. The packet filters may, for example, beconfigured by the test system via layer 3 control messages specified bythe radio or wired interface under test. For example, for UTRA, E-UTRAand GPRS, the packet filters may be configured by UL TFT informationsent in layer 3 control messages.

When a bearer mapping unit 333 is used, there is no need for more thanone radio bearer loop back (RB LB) entity in the LB function unit 332.This is because in such an implementation, all the DL loopback data isterminated in the UE LB function 332 and all the UL loopback data isdirectly forwarded to the bearer mapping unit 333, which handles thefurther distribution to the correct radio bearer.

The loopback functionality resides above the access functionality of thecommunication device, i.e. in a non-access stratum. This enablesloopback functionality testing of bearer mapping, for example after alink disconnection or a handover event. Thus, the loopback point isabove the functionality handling the mapping between SDF(s) (or PDPcontext(s)) and bearer(s) in the communication device.

In a situation where more than one SDFs (or PDP contexts) areestablished there is commonly one bearer that is not associated with anypacket filter. Thus, all packets that are not filtered out by any of thepacket filters should be sent on this bearer. However, not beingexplicitly associated with any packet filter may also be viewed as apacket filter (e.g. the complement of the union of the packet filtersassociated with the other bearers). Therefore, when this applicationmentions units of data being associated with different service dataflows, each of the units of data including information representing theservice data flow associated with the unit of data, and verifying thateach of the units of data is transmitted on a correct bearercorresponding to the service data flow associated with the respectiveunit of data according to the one or more uplink packet filters, it isunderstood to also embrace the situation of one bearer not beingassociated with any packet filter as explained above.

The LB function unit may include functionality to alter some of theheader fields of received IP packets before sending them in the uplink.This may include calculating the IP checksum before it is inserted intothe header. FIG. 5 illustrates the IPv4 header fields. As an example, ifan IP packet is increased or decreased in size as explained above, thenthe IP header fields “Total Length” and “Header Checksum” are updated.

FIG. 4 is a signaling flowchart illustrating example method stepsaccording to some embodiments of the invention and the interactionbetween a test system 400 and a communication device 410 under test.

The test method illustrated in FIG. 4 is particularly suitable forverification of communication device behavior in relation to packetfilers within one radio access technology and/or after RAT handover(e.g. as configured by UL TFT when the radio link is established).

The test system 400 is configured to send data to the communicationdevice 410 in a downlink and the communication device 410 is configuredto return data received in the downlink for transmission in the uplinkto the test system 400.

In step 401, the test system establishes a radio link, and configuresthe radio bearer(s), control channel(s), and packet filter(s) to be usedfor the test.

In step 402, the test system triggers activation of the dedicated testloop function of the communication device, which responds to theactivation triggering in step 411. The activation in steps 402 and 411may comprise closing of a test loop. The activation may also compriseconfiguring the test loop function. Alternatively, the test loopfunction may be partly or fully pre-configured.

In step 403, the test system sends data (e.g. IP packets) in thedownlink to the communication device, which receives the data in step412. In step 412, the data received by the communication device may alsoundergo various processing by the communication device, for example suchinternal device reception data processing as known in the art. Eachpacket sent in the downlink includes header information that simulatesthat the IP packets represent different service data flows. After step412 (e.g. in connection with steps 416 and 407), verification that thereception of data and the processing of the received data are performedcorrectly by the communication device may be undertaken.

The dedicated test loop function is configured to transfer all or partof the data received in downlink for transmission on a radio bearer inthe uplink (step 414). When data is returned for transmission in theuplink, the communication device maps the IP packets to differentbearers based on the packet filter configuration.

After the communication device has transferred the data for transmissionin the uplink in step 414, the same data is transmitted in the uplink instep 416, and receiver by the test system in step 407. When the testsystem receives the data in step 407, it can do verification of thedata. The verification may simply comprise verifying that uplinktransmission takes place without verifying that the data is actuallycorrect, or it may comprise also verifying that the data is transmittedcorrectly in the uplink. The verification in step 407 may compriseverifying that each of the IP packets are transmitted on the correctuplink bearer in accordance with the packet filter configuration and theIP header information set by the test system.

As mentioned above, the verification may additionally or alternativelycomprise indirect verification of correct DL reception and/orprocessing. Such verification is indirect because the verification isperformed via returned (UL) data. The test system compares the returnedUL data with the data that was sent in the DL. If, for example, thereturned UL data is identical with the data that was sent in the DL,this may be verification that the reception and processing of the DLdata was performed correctly. Another example is where a test systemsends DL data with erroneous header information. Then, the communicationdevice should not accept the data and correct operation of thecommunication device may be verified in that no data is returned in theUL.

When the test session is completed, the test system triggers thedeactivation (opening) of the test loop in step 408, and thecommunication device responds to the deactivation triggering in step417. In step 409, the radio link is disconnected.

The communication device 410 may be further configured to return datafor transmission in the uplink only after a specific event has occurred.This enables control over the relative timing of certain events andactions in the test procedure. For example, the test system may triggera disconnection of the link before the specific event has occurred andthereby ensure that the communication device will have data pending fortransmission when the link has been disconnected. Thereby the testsystem is able to ensure the possibility to verify the connectionre-establishment procedure and that data is correctly transmitted afterthe connection re-establishment.

Thus, the dedicated test loop function may optionally also be configuredto transfer all or part of the data received in downlink fortransmission on a radio bearer in the uplink (step 414) only after aspecific event has occurred (step 413).

The specific event may be the elapse of a specific amount of time fromthe time the data has been received. This may be realized as a timer inthe test loop function. The time may be pre-configured or it may beconfigured (e.g. by the test system) as part of the activation in steps402 and 411. It may also be configured by a specific command entered oneither or both of the test system and the communication device prior toor after the test function has been activated in steps 402 and 411.

The specific event may also be another event such as the transmission ofa specific command from the test system to the communication device(step 405), the registration of an action (such as pressing a key)performed by a test operator on either or both of the test system (step405) and the communication device. The specific event may also be thedisconnection (404) of the radio link established in step 401.

The type of event (elapsed time, command, operator action, linkdisconnection, etc.) may be pre-configured or it may be configured (e.g.by the test system) as part of the activation in steps 402 and 411. Thetest system may send an indicator to the communication system thatdefines the type of event and/or the amount of time to elapse. It mayalso be configured by specific commands entered on either or both of thetest system and the communication device prior to or after the testfunction has been activated in steps 402 and 411.

The solution with a specific elapsed time has little impact on theimplementation of the communication device.

Before the specific event has occurred, the test system may trigger adisconnection of the radio link between the test system and thecommunication device under test in step 404. When the test loop functionin the communication device has returned data received in downlink fortransmission in the uplink (step 414), the radio link may thus bedisconnected. Since the communication device is disconnected and hasdata pending for transmission in the uplink, a procedure to re-establishthe connection is triggered in step 415.

The test system verifies, in step 406, that the communication deviceperforms the connection re-establishment procedure correctly.

The disconnection in step 404 may, for example, simulate a radio linkfailure. Alternatively or additionally, the test system may, before thespecific event has occurred, simulate handover to other intra-systemcell or to other RAT and verify that the communication device performsthe corresponding procedures correctly. In this case, the specific eventmay comprise any of the examples as referred to above or it may comprisethe handover in itself.

As mentioned, the test loop function in the communication device may beconfigured to return part or all of the data received on the downlink.For example, some of the data sent in the downlink may be intended forthe uplink (e.g. for testing uplink behavior) and is thus returned,while some of the data sent in the downlink may be intended for someother purpose (e.g. for testing of downlink reception) and is thus notreturned. Furthermore, if the data is transmitted as packets (e.g. IPpackets) in the downlink, it may be only the payload of the packet thatis returned for transmission in the uplink. Other content of the packet(such as header information), may be removed, added or changed beforetransmission in the uplink. The size of the payload may also be changed,for example by repeating the entire or part of the payload, bytruncating or puncturing the payload. Furthermore, the size of theentire packet may be changed, if for example the header is changedand/or the size of the payload is changed.

As mentioned the test loop function may be partly or fullypreconfigured. There may be a dedicated preconfigured test loop functionfor each relevant scenario. Alternatively, there may be a single (or afew) test loop functions, which are configured for a specific scenarioas part of the activation in steps 402 and 411.

Links and bearers have been described above as radio links and radiobearers, but embodiments of the invention are equally applicable towired communication systems.

Some embodiments of the invention combine the optional alternatives ofelapsed time and another event triggering in the same solution. Forexample, the data may be transferred in step 414 directly after an eventtrigger (405) but at the latest at the elapse of a specific amount oftime.

If it is desired to verify the communication device behavior for packetfiltering after, for example, a radio access technology handover hasoccurred, the following steps may be added to the method.

The test system may initiate a change of radio access technology bysending the corresponding handover command to the communication device(step 404′). Alternatively or additionally, the test system may simulatea handover to other intra-system cell. A handover procedure is thustriggered and responded to by the communication device in step 415′. Thetest system verifies, in step 406′, that the communication deviceperforms the handover procedure correctly.

In step 403′, the test system sends further data (e.g. IP packets) inthe downlink to the communication device, which receives the furtherdata in step 412′. In step 412′, the data received by the communicationdevice may also undergo various processing by the communication device,for example such internal device reception data processing as known inthe art. Again, each packet sent in the downlink includes headerinformation that simulates that the IP packets represent differentservice data flows.

The dedicated test loop function transfers all or part of the furtherdata for transmission on a radio bearer in the uplink (step 414′). Whenthe further data is returned for transmission in the uplink, thecommunication device maps the IP packets to different bearers based onthe packet filter configuration.

After the communication device has transferred the further data fortransmission in the uplink in step 414′, the same further data istransmitted in the uplink in step 416′, and receiver by the test systemin step 407′. When the test system receives the further data in step407′, it can do verification of the further data. The verification maysimply comprise verifying that uplink transmission takes place withoutverifying that the further data is actually correct, or it may comprisealso verifying that the further data is transmitted correctly in theuplink. The verification in step 407′ may comprise verifying that eachof the IP packets of the further data is transmitted on the correctuplink bearer in accordance with the packet filter configuration and theIP header information set by the test system, i.e. that the bearermapping is correct even after the handover.

Embodiments of the invention make it possible to verify communicationdevice compliance with scenarios for mobile originated data. This isapplicable to, for example, scenarios for connection re-establishmentwhen data is pending for transmission in the communication device. Theverifications of compliance to such scenarios are important to securecompliance of the communication device with standardized behavior to beable to guarantee the quality of service that end users will expect.

Embodiments of the invention also make it possible to test datacontinuation during mobility cases, such as RAT handover, e.g. betweenE-UTRAN to E-UTRA, and cell handover.

Embodiments of the invention also make it possible to test packet filter(e.g. UE UL TFT) functionality and data continuation during mobilitycases, such as RAT handover, e.g. between E-UTRAN to E-UTRA, and cellhandover.

The described embodiments of the invention and their equivalents may berealised in software or hardware or a combination thereof. They may beperformed by general-purpose circuits associated with or integral to acommunication device, such as digital signal processors (DSP), centralprocessing units (CPU), co-processor units, field-programmable gatearrays (FPGA) or other programmable hardware, or by specialized circuitssuch as for example application-specific integrated circuits (ASIC). Allsuch forms are contemplated to be within the scope of the invention.

The invention may be embodied within an electronic apparatus comprisingcircuitry/logic or performing methods according to any of theembodiments of the invention. The electronic apparatus may, for example,be a portable or handheld mobile radio communication equipment, a mobileradio terminal, a mobile telephone, a communicator, an electronicorganizer, a smartphone, a computer, a notebook, or a mobile gamingdevice.

According to some embodiments of the invention, a computer programproduct comprises a computer readable medium such as, for example, adiskette or a CD-ROM. The computer readable medium may have storedthereon a computer program comprising program instructions. The computerprogram may be loadable into a data-processing unit, which may, forexample, be comprised in a mobile terminal or a test system. When loadedinto the data-processing unit, the computer program may be stored in amemory associated with or integral to the data-processing unit.According to some embodiments, the computer program may, when loadedinto and run by the data-processing unit, cause the data-processing unitto execute method steps according to, for example, the methods shown inany of the FIGS. 1 and 4.

The invention has been described herein with reference to variousembodiments. However, a person skilled in the art would recognizenumerous variations to the described embodiments that would still fallwithin the scope of the invention. For example, the method embodimentsdescribed herein describes example methods through method steps beingperformed in a certain order. However, it is recognized that thesesequences of events may take place in another order without departingfrom the scope of the invention. Furthermore, some method steps may beperformed in parallel even though they have been described as beingperformed in sequence.

In the same manner, it should be noted that in the description ofembodiments of the invention, the partition of functional blocks intoparticular units is by no means limiting to the invention. Contrarily,these partitions are merely examples. Functional blocks described hereinas one unit may be split into two or more units. In the same manner,functional blocks that are described herein as being implemented as twoor more units may be implemented as a single unit without departing fromthe scope of the invention.

It is also emphasized that features of one embodiment may be combinedwith features of another embodiment in various working combinations.

Hence, it should be understood that the limitations of the describedembodiments are merely for illustrative purpose and by no meanslimiting. Instead, the scope of the invention is defined by the appendedclaims rather than by the description, and all variations that fallwithin the range of the claims are intended to be embraced therein.

The invention claimed is:
 1. A method for verifying compliance of acommunication device with one or more requirement specifications, themethod comprising: establishing a link between a test system and thecommunication device, wherein the establishing comprises configuring oneor more bearers and one or more control channels; closing a test loopcomprising the test system and the communication device, wherein theclosing comprises activating a test loop function of the communicationdevice; sending data in a downlink of the test loop from the test systemto the communication device; receiving the data on the downlink at thecommunication device; transferring at least some of the data to anuplink transmission arrangement of the communication device after aspecific event has occurred, wherein the specific event is used tocontrol when the communication device transfers at least some of thedata received on the downlink to the uplink transmission arrangement andis at least one of: an elapse of a predefined amount of time sincehaving received the data at the communication device on the downlink,wherein the predefined amount of time is controllable by the testsystem; a transmission of a specific command from the test system to thecommunication device; a registration of an action performed by a testoperator on either or both of the test system and the communicationdevice; and a disconnection of the radio link; and verifying, at thetest system, transmission in the uplink of the test loop from thecommunication device to the test system.
 2. The method of claim 1,wherein verifying transmission in the uplink comprises verifying thatthe data transferred to the uplink transmission arrangement istransmitted correctly in the uplink by the communication device.
 3. Themethod of claim 1, wherein the specific event is the elapse of aspecific amount of time from the reception of the data.
 4. The method ofclaim 1, wherein the specific event is a transmission of a specificcommand from the test system to the communication device.
 5. The methodof claim 1, wherein the specific event is a registration of a testoperator action performed on at least one of the test system and thecommunication device.
 6. The method of claim 1, wherein the specificevent is a disconnection of the link and further comprising: verifying,at the test system, that a link re-establishment procedure is executedcorrectly by the communication device.
 7. The method of claim 1, furthercomprising: disconnecting the link after sending the data in thedownlink and before the specific event has occurred; and verifying, atthe test system, that a link re-establishment procedure is executedcorrectly by the communication device.
 8. The method of claim 1, whereinthe link is a radio link and the bearers are radio bearers, and furthercomprising: simulating an intra-system cell handover event bytransmitting a cell handover command from the test system to thecommunication device after the step of sending the data in the downlinkand before the specific event has occurred; and verifying, at the testsystem, that an intra-system cell handover procedure is executedcorrectly by the communication device.
 9. The method of claim 1, whereinthe link is a radio link and the bearers are radio bearers, and furthercomprising: simulating a radio access technology handover event bytransmitting a radio access technology handover command from the testsystem to the communication device after the step of sending the data inthe downlink and before the specific event has occurred; and verifying,at the test system, that a radio access technology handover procedure isexecuted correctly by the communication device.
 10. The method of claim1, wherein activating the test loop function comprises sending anindicator defining the specific event from the test system to thecommunication device.
 11. The method of claim 1, wherein: establishingthe link between the test system and the communication device furthercomprises configuring one or more uplink packet filters; sending data inthe downlink of the test loop from the test system to the communicationdevice comprises sending units of data associated with different servicedata flows and including, in each of the units of data, informationrepresenting the service data flow associated with the unit of data; andverifying transmission in the uplink comprises verifying that each ofthe units of data is transmitted, by the communication device, on acorrect bearer corresponding to the service data flow associated withthe respective unit of data according to the one or more uplink packetfilters.
 12. The method of claim 1, wherein said transferring comprisestransferring at least some of the data to the uplink transmissionarrangement responsive to determining that the specific event hasoccurred.
 13. The method of claim 1, wherein the specific event iscontrolled by the test system as part of controlling a loopback delay ofthe test loop.
 14. The method of claim 1, wherein the specific event isan elapse of a predefined amount of time as determined by a timer of thecommunication device that is started in response to the communicationdevice receiving the data on the downlink and is used to trigger thecommunication device to transfer at least some of the data received onthe downlink to the uplink transmission arrangement.
 15. The method ofclaim 1, further comprising: prior to activating the test loop functionof the communication device, configuring the communication device withinformation that defines said specific event, said specific eventgoverning the timing of when the device is to perform said transferring.16. The method of claim 1, further comprising: contemporaneous withactivating the test loop function of the communication device,configuring the communication device with information that defines saidspecific event, said specific event governing the timing of when thedevice is to perform said transferring.
 17. The method of claim 1,further comprising: after activating the test loop function of thecommunication device, configuring the communication device withinformation that defines said specific event, said specific eventgoverning the timing of when the device is to perform said transferring.18. The method of claim 1, wherein the specific command is entered on atleast one of the test system and the communication device prior to orafter the test function has been activated.
 19. The method of claim 1,wherein the registration of the action performed by the test operator isa pressing of a key of at least one of the test system and thecommunication device.
 20. A computer program product stored on anon-transitory computer readable medium and comprising programinstructions that, when executed by a data- processing unit of a testsystem connectable to a communication device, cause the test system toverify compliance of the communication device with one or morerequirement specifications by: establishing a link between the testsystem and a communication device, wherein the establishing comprisesconfiguring one or more bearers and one or more control channels;closing a test loop comprising the test system and the communicationdevice, wherein the closing comprises activating a test loop function ofthe communication device; sending data in a downlink of the test loopfrom the test system to the communication device; verifying transmissionin an uplink of the test loop from the communication device to the testsystem; and wherein activating the test loop function comprises sendingan indicator defining a specific event from the test system to thecommunication device, and wherein the specific event is used to controlwhen the communication device transfers at least some of the datareceived on the downlink to an uplink transmission arrangement of thecommunication device and is at least one of: an elapse of a predefinedamount of time since having received the data at the communicationdevice on the downlink, wherein the predefined amount of time iscontrollable by the test system; a transmission of a specific commandfrom the test system to the communication device; a registration of anaction performed by a test operator on either or both of the test systemand the communication device; and a disconnection of the radio link. 21.The computer program product of claim 20, wherein the programinstructions further cause the test system to verify said compliance by:disconnecting the link after sending the data in the downlink and beforethe specific event has occurred; and verifying that a linkre-establishment procedure is executed correctly by the communicationdevice.
 22. A test system connectable to a communication device and forverifying compliance of the communication device with one or morerequirement specifications, comprising: a transmitter, a receiver andprocessing circuitry; the processing circuitry configured to: establish,via the transmitter, a link between the test system and thecommunication device, wherein the establishing comprises configuring oneor more bearers and one or more control channels; and close, via thetransmitter and the receiver, a test loop comprising the test system andthe communication device, wherein the closing comprises activating atest loop function of the communication device; the transmitterconfigured to send data in a downlink of the test loop from the testsystem to the communication device; the receiver and the processingcircuitry configured to verify transmission in an uplink of the testloop from the communication device to the test system; and theprocessing circuitry configured to send, via the transmitter, anindicator defining a specific event from the test system to thecommunication device as part of the activation of the test loopfunction, wherein the specific event is used to control when thecommunication device transfers at least some of the data received on thedownlink to an uplink transmission arrangement of the communicationdevice and is at least one of: an elapse of a predefined amount of timesince having received the data at the communication device on thedownlink, wherein the predefined amount of time is controllable by thetest system; a transmission of a specific command from the test systemto the communication device; a registration of an action performed by atest operator on either or both of the test system and the communicationdevice; and a disconnection of the radio link.
 23. The test system ofclaim 22, wherein the processing circuitry is further configured toverify that the data is transmitted correctly in the uplink by thecommunication device.
 24. The test system of claim 22, wherein theprocessing circuitry is further configured to: disconnect the link afterthe transmitter has sent the data in the downlink and before thespecific event has occurred; and verify that a radio linkre-establishment procedure is executed correctly by the communicationdevice.
 25. The test system of claim 22, wherein the link is a radiolink and the bearers are radio bearers, and wherein the processingcircuitry is further configured to: simulate an intra-system cellhandover event by transmitting, via the transmitter, a cell handovercommand to the communication device after the transmitter has sent thedata in the downlink and before the specific event has occurred; andverify that an intra-system cell handover procedure is executedcorrectly by the communication device.
 26. The test system of claim 22,wherein the link is a radio link and the bearers are radio bearers, andwherein the processing circuitry is further configured to: simulate aradio access technology handover event by transmitting, via thetransmitter, a radio access technology handover command to thecommunication device after the transmitter has sent the data in thedownlink and before the specific event has occurred; and verify that aradio access technology handover procedure is executed correctly by thecommunication device.
 27. The test system of claim 22, wherein the datacomprises units of data associated with different service data flows,and wherein the processing circuitry is further configured to:configure, via the transmitter, one or more uplink packet filters;include, in each of the units of data, information representing theservice data flow associated with the unit of data; and verify that eachof the units of data is transmitted, by the communication device, on acorrect bearer corresponding to the service data flow associated withthe respective unit of data according to the one or more uplink packetfilters.
 28. A communication device comprising a test loop functionarrangement and an uplink transmission arrangement, the test loopfunction arrangement comprising: a loop back function circuit configuredto receive data sent in a downlink of a test loop from a test system andto transfer at least some of the data to the uplink transmissionarrangement; and a test control function circuit configured to: receivean indicator defining a specific event from the test system as part ofactivating the test loop function arrangement, wherein the specificevent is used to control when the communication device transfers atleast some of the data received on the downlink to the uplinktransmission arrangement and is at least one of: an elapse of apredefined amount of time since having received the data at thecommunication device on the downlink, wherein the predefined amount oftime is controllable by the test system; a transmission of a specificcommand from the test system to the communication device; a registrationof an action performed by a test operator on either or both of the testsystem and the communication device; and a disconnection of the radiolink; and defer transferring by the loop back function circuit of thedata to the uplink transmission arrangement until after the specificevent has occurred.
 29. The communication device of claim 28, whereinthe data comprises units of data associated with different service dataflows, and wherein the communication device further comprises a bearermapping circuit configured to map each of the units of data to a correctbearer corresponding to the service data flow associated with therespective unit of data according to one or more uplink packet filters.30. The communication device of claim 28, wherein the elapse of thepredefined amount of time is determined by a timer of the communicationdevice that is started in response to the communication device receivingthe data on the downlink and is used to trigger the communication deviceto transfer at least some of the data received on the downlink to theuplink transmission arrangement.
 31. The communication device of claim28, wherein the specific command is entered on at least one of the testsystem and the communication device prior to or after the test functionhas been activated.
 32. The communication device of claim 28, whereinthe registration of the action performed by the test operator is apressing of a key of at least one of the test system and thecommunication device.
 33. The communication device of claim 28, whereinthe specific event is the disconnection of the link triggered by thetest system; and wherein the test control function circuit is furtherconfigured to perform a link re-establishment procedure responsive tothe disconnection of the link triggered by the test system.